Edexcel S3 2017 June — Question 8

Exam BoardEdexcel
ModuleS3 (Statistics 3)
Year2017
SessionJune
TopicContinuous Uniform Random Variables
TypeSample statistics from uniform

8. The random variable \(X\) has a continuous uniform distribution over the interval \([ \alpha + 3,2 \alpha + 9 ]\) where \(\alpha\) is a constant. The mean of a random sample of size \(n\), taken from this distribution, is denoted by \(\bar { X }\)
  1. Show that \(\bar { X }\) is a biased estimator of \(\alpha\)
  2. Hence find the bias, in terms of \(\alpha\), when \(\bar { X }\) is used as an estimator of \(\alpha\) Given that \(Y = \frac { 2 \bar { X } } { 3 } + k\) is an unbiased estimator of \(\alpha\)
  3. find the value of the constant \(k\) A random sample of 8 values of \(X\) is taken and the results are as follows
    4.8
    5.8
    6.5
    7.1
    8.2
    9.5
    9.9
    10.6
  4. Use the sample to estimate the maximum value that \(X\) can take.
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